The present disclosure herein relates to Complementary Metal-Oxide-Semiconductor (CMOS) image sensors. An image sensor is a device that converts optical images into electrical signals. With increased development of the computer and communications industries, there is an increased demand for high performance image sensors in a variety of applications such as digital cameras, camcorders, personal communication systems, gaming machines, security cameras, micro-cameras for medical applications, and/or robots.
CMOS image sensors may be operated using a relatively simple operation method and may be configured to have signal processing circuits integrated on a single chip, thus enabling products that include the CMOS image sensors to be scaled down. In addition, CMOS image sensors may operate with relatively low power consumption. Thus, CMOS image sensors may be applicable to portable electronic devices. Furthermore, CMOS image sensors may be fabricated using CMOS fabrication techniques, which may reduce manufacturing costs. Moreover, CMOS image sensors may provide high resolution images. Accordingly, the use of CMOS image sensors has increased.